Modern cellular telephones are becoming more flexible and, essentially “software defined”. Thus, they often operate at different frequencies, modulation types and data rates in a completely transparent fashion to the user. Often, these phones have short message services and/or internet browsing capabilities. In general, communication data rates and signal bandwidths have increased with the desire to operate them as PDA's (personal digital assistants). In addition, it is quite common for even generic cellular telephones to have an embedded GPS reception capability, which often isn't directly available to the user, but is employed for emergency position finding or other purposes. Often the signal processing in cellular telephones is implemented in programmable DSP's or digital signal processing chips. This lends great flexibility to said cellular telephones.
These cellular telephones have rechargeable batteries, which are often recharged at night, which minimizes the volume and mass of the battery.
Separately, there has of late been a very large increase in the use of GPS devices for a variety of purposes, very often automobile navigation, where they are extremely effective. There has also been interest in location of persons, animals, and things. In many cases, the GPS solution to this is impractical, because of energy consumption, physical size, and/or inadequate access to the sky overhead.
Some methods for locating an object are known in the art. A missing vehicle locator system is described in U.S. Pat. No. 5,418,736 issued to Bird. The vehicle locator system uses one or more GPS systems in conjunction with a GPS antenna, a receiver/transmitter, a telephone with associated antennas, and a modem mounted in a vehicle whose position is to be monitored. A paging request is issued and received by a paging responder in the vehicle. The paging request causes the modem to interrogate the GPS receiver to determine the current position of the vehicle. The current position of the vehicle is transmitted via a cellular telephone link to notify a vehicle location service center of the current location of the vehicle. Other known location determination techniques include the use of a Loran or a Glonass satellite based system.
Another object location system is described in U.S. Pat. No. 5,576,716 to Sadler for locating lost or stolen property. This location system includes a GPS module, a microcomputer, a modem, and a telephone, all of which must be installed in the vehicle. The system described regularly and automatically computes the position of the property for transmission via the phone link to a central receiver/transmission station.
Low power transmissions are subject to signal corruption due to noise, static, and signal interference. Extracting information from a signal in the presence of such interference and noise is very difficult when the information signal is of the same order of magnitude as the noise sources. The presently described invention identifies various noise problems from the conventional solutions and provides a new and novel system, method, and apparatus that is arranged to extract signals from a transmission using very low power in a small scale object location system.